Piezoelectric substrates are capable of converting a physical stimulus such as pressure, acceleration, strain, or force into an electrical signal. In general, piezoelectric sensors show a proportional electrical output signal, relative to the applied force. Piezoelectric materials are used in several industries including the medical, aerospace and automotive industries.
One area where piezoelectric materials have been applied is in the area of surface acoustic wave resonator technology. Surface acoustic wave (SAW) resonators have been widely used in various industries, including the communications industry. A typical SAW resonator will consist of an electrode structure applied to a piezoelectric substrate. Materials such as aluminum and other lightweight metals are commonly used for the electrode material on SAW resonators.
Unfortunately, for high temperature applications, typical SAW resonators are unsatisfactory. This is due to several reasons including the relatively low melting temperature of the metal electrodes typically used in the art. Use of higher-melting temperature electrode materials has proven problematic because of various interference effects resulting from the use of these materials, including the generation of spurious modes.